This invention concerns a method of pollution control obtained by growing unicellular and similar algae with the aid of an organic waste nutrient medium, including a phosphorus-providing substance and nitrogen-providing material. In another manner of expression, the invention concerns a method of pollution control wherein unicellular and similar algae, such algae being a good source of protein, are grown in symbiotic relationship with aerobic bacteria on nitrogen-providing or protein-providing aqueous waste materials such as portions of sewage, cannery wastes, etc., in a way that produces purified water, an algal mass high in protein, and free oxygen, which is liberated to the atmosphere. In another aspect, the invention relates to an apparatus especially suitable for admixing algae and nutrient waste material and exposing portions of the admixture to intermittent light exposure and darkness of desired time length.
Pollution control is one of the most important factors in preserving a balanced environment. There are many methods of removing pollution from municipal wastes, ranging from simple municipal primary treatment, to complex biological and chemical primary or secondary or tertiary treatment, such as the Tahoe Public Utilities Department experimental plant, for instance. All these systems are primarily concentrated on removal of biological oxygen demand (BOD) wastes. BOD wastes are those wastes which require oxygen and take it from the water.
Any attempt to purify waste water cannot fail to help the environment, but this simple prior-art removal of pollutants cannot be considered as efficient in a balanced ecological system. In fact, the disposal of certain wastes in streams and lakes can have a beneficial effect. In some cases, thermal pollution has had a favorable effect on trout population. However, most wastes introduced into the environment have a deleterious effect on the water. It is essential to ascertain the total ecological impact of water treatment. Ideally, the object of any pollution treatment should be to return the wastes to the environment in the least harmful way, while extracting or converting as much waste as possible to usable form.
It is among the objects of this invention to provide a balanced treatment of waste, not only to provide pure water, but to use waste as a resource to produce a source of protein. A further object of the invention is to produce oxygen and to liberate it into the atmosphere in substantial quantities. Still further objects are to enable the treatment of wastes to be carried on with minimized costs in material, equipment, operation and recovery. It is a specific object to produce, from aqueous wastes, purified water which can be used for domestic purposes (after chlorination), industrial cooling, irrigation or as return to ground water or for all such purposes.